The 15 Largest Armies in History

Located in what is modern-day inland northern China, the earliest Chinese dynasty maintained what is believed to have been the first fighting force in history to top 10,000 soldiers. The only Bronze Age army that came close to this was the Uruks of Mesopotamia, whose army is estimated to have numbered approximately 4,000 troops a millennium earlier.

Ramses II is believed by many scholars to be the pharaoh referred to in the Exodus story of the Old Testament – the one who, according to the Hebrew Bible, sent chariot warriors to pursue Moses and the fleeing Jews only to be drowned in the Red Sea. The historical Ramses II certainly had a large army used to secure the borders of his empire against nomadic invaders, to battle the Hittites of Anatolia, and to beat back the Sea Peoples who were raiding in the Eastern Mediterranean.

The First Persian Empire stretched from Libya to Central Asia and included Egypt, Anatolia (Turkey), and parts of northern India. At its peak, it had a population of 49.5 million people. Using his skills in military strategy and benevolence toward those he conquered, Cyrus the Great expanded his ancestral homeland in Iran into this massive empire, growing his army to 500,000 soldiers — the first armed force to reach that benchmark.

It would take about 200 years after Cyrus the Great of Persia for a second army to emerge with an estimated 500,000 soldiers. This time it was the Mauryan Empire, founded by Chandragupta Maurya in the wake of the destruction left by Alexander the Great in India’s Punjab region. The empire made up most of the subcontinent and maintained relative peace among the local kingdoms for more than a century.

Estimates vary considerably regarding the size of the Roman Army at its peak, and 500,000 is considered at the upper end of the estimate range. Part of this variation is due to the way the Roman Empire classified soldiers. Local native non-Roman units could join with the imperial army, and non-citizen inhabitants of the Roman Empire could be auxiliaries, but only Roman citizens could be members of core elite legions.

China’s Tang Dynasty, known for having a cosmopolitan outlook, expanded across a massive territory gained by military campaigns of the earliest rulers of the period. The first army to top 600,000 troops was built on a system known as Fubing, which included conscripting fighters to serve one month out of every five or two months out of every eighteen based on how far they lived from the capital. But this system could only supply the military for short campaigns and it eventually collapsed.

Estimates vary widely on the size of Genghis Khan’s army, with some claims of a million fighters. The Mongols were pastoral nomads, so it is possible the high-end estimates are based on the size of Mongol encampments. A typical Mongol siege on a city or stronghold started with far fewer soldiers, about three to five divisions of 10,000 men behind a line of horsemen deftly deploying their distinctive composite bows. Mongol fighting tactics included mounted couriers on the battlefront and a complex signaling system that allowed for highly flexible maneuvering, including retreating and regrouping.

China’s Ming Dynasty that emerged following the harsh rule of the Mongol Yuan dynasty had, at its height, the first million-soldier army. It was indisputably the largest armed force in the world at the time, including a massive naval force. In the early 15th century, Ming emperor Zhu Di pointed his army south to conquer what is Vietnam today.

Napoleon Bonaparte’s march across Europe was enabled by conscription, allowing the Corsican conqueror to deploy an army larger than today’s Chinese armed forces. The Napoleonic Wars raged for 12 years, and combat deaths from these battles are estimated to have been between 2.5 million and 3.5 million soldiers. France, Britain, Russia, Prussia, Austria, Spain, and Portugal each lost more than 100,000 fighters battling Napoleon’s forces.

At the outset of World War I in 1914, the five Allied Powers vastly outnumbered the Central Powers, with a combined 3.2 million troops versus Austria-Hungary’s 450,000 and the Wehrmacht’s 1.9 million soldiers. But as the war quickly escalated, as did the number of soldiers.

The Germans invaded Poland on Sept. 1, 1939, with nearly 1.8 million troops. By the summer of 1943, about 4 million Axis fighters, mostly Germans, were battling more than 6.7 million Russians. At its peak strength, the Soviet Union had an estimated 11 million soldiers in 1943, though some estimates put Russian troop strength as high as 13.2 million at its peak. The Soviets lost between 8 million and over 10 million soldiers beating back the Germans and playing a crucial role in defeating the Axis.

Estimates vary about the size of the Nazi forces at its peak during World War II. We know that about 4 million Axis fighters, most of whom were German, were sent by Hitler to invade Russia. The Third Reich is estimated to have had a fighting army of 12.1 million at its peak in 1944.

At the onset of World War II, the United States had a small standing army, but it would rapidly grow as it became clear the U.S. would need to get involved in the global conflict, especially following the bombing of Pearl Harbor. By 1945, the U.S. Armed Forces had grown to 12.2 million.

World War II saw a historical peak in the number of soldiers fighting in that years-long global conflict. Since then, the size of standing or fighting armies has shrunk considerably. In 1981, the world’s largest army was under the control of the Soviet Union, which at the time had commenced its invasion of Afghanistan.

The largest number of active-duty personnel in the world today belongs to the People’s Republic of China. The world’s largest country by population has been asserting its territorial boundaries in the South China Sea, angering regional neighbors. It also maintains détente with India, has an ongoing dispute with Japan over a group of islands, and is on guard against any efforts regarding Taiwanese independence.